The truth is that MIUI provides a lot of customization to our Xiaomi devices, personalizations that are not available in stock Android. And as you already know, the new features of the Global Stable versions go first from Global Beta. The latest and latest MIUI 10 Global Beta 9.3.21 provides a number of fixes, including the issue of notification icons in the latest Xiaomi devices, such as Xiaomi Mi 9 and Redmi Note 7.
As XDA Developers, which they listed in Redmi Note 7 Pro, when a notification arrives, the alert icon appears in the status bar for a short time. But after a few seconds, it disappears, even if the warning is still in the notification screen. This makes it difficult to judge if you have new messages that want your attention.
Currently, the download links to Mi 9, Mi 8 Pro, Redmi Note 7 are not available. On the link to the source you can find the links for the other devices